Combination gas and liquid fuel burner



Dec. 17, 1946.. 2. J. HAUZVlC 2,412,579

COMBINATION GAS AND LIQUID FUEL BURNER Filed Jan." '13, 1945 v a Sheets-Sheet 1 if 5/ 4 0 67/46 56 (if /i 24 /i a 20 1/fl if 5/ 4Q 22' M l. t, 2 r-70 2? 705 if Dec. 17, 1946,

Z. J. HAUZ VIC COMBINATION GAS'AND LIQU ID FUEL BURNER Filed Jan. 13, 1945 3 Sheets-Sheet 2 Dec. 17, 1946. v 2. J. HAUZVIC 2,412,579

COMBINATION GAS AND LIQUID FUEL BURNER Filed Jan. 13,- 1945 3 Sheets- Sheet 3 FIEAl- FIE44- FIEJB;

LLQU/O F054 4440/? Fug ggu/g all F |=|E-15- F1549- 5 gay/0 Fua Law F054 5455005 fZ/fl 455005 fuzz Z v 6455005 fZ/E;

1-15.17, F'IEQE'L Mum F052 52.055005 fi/H 41005 fuzz uvmvrox: 20mm j flqz/zwc,

Patented ese 1?, 1946 S PATENT orrlca COMBINA'IIGN GAS AND LIQUKD FUEL BURNER 6 claims. 3

The present invention relates to structural features of design and arrangement of the component parts of a burner adapted to handle both liquid and gaseous fuels. While not limited thereto, the burner of the present invention is peculiarly well suited for use in an open hearth steel making furnace fired with liquid fuel, such as fuel oil or tar,

mixed with a gaseous fuel, such as coke oven gaS.

clogged with foreign matter, with the result that the gaseous fuel is not properly shielded and therefore has a tendency to cause an early destruction of the roof and other parts of the furnace. The burner of the present invention'aims to overcome the above and other inherent defects in prior types of burners.

One object of the invention is to provide a burner so constructed and arranged that the clogging of :both the liquid and the gas fuel nozzles is minimized, thus insuring long periods of efficient operation. For the necessary infrequent cleanings of the burner; easy and convenient access is provided.

Another object of the invention is to provide a construction and arrangementv wherein most of the length of the atomized liquid fuel supply pipe is enclosed in the gaseous fuel supply pipe thus exposing only a short length at the nozzle end to direct cooling effect of the water or other coolant which is circulated through the burner shell.

Another object is to provide an outlet for the gaseous fuel of such size and shape and bearing such relationship to the liquid fuel nozzle that the best combustion propagation and heat utilization are secured when using gaseous fuel in any desired proportion to the liquid fuel. a

A further object of the invention is to provide means for discharging a scavenging jet of steam in the region of the outlet orifice of the gaseous fuel pipe so as to effectively eject accumulations of foreign matter which may have lodged therein during the cycle of furnace operation when the burner is inactive.

An additional object of the invention is to provide a rugged design of burner wherein many of the component parts can be economically constructed of lengths of standard gauge commerclally obtainable pipe and standard fittings.

. r A further object is to so construct and arrange the various component parts of the burner herein shown that they individually and collectively perform the functions hereinafter described.

For a more complete understanding of the invention, reference should be made to the following detailed description, the accompanying drawings, and the appended claims.

In the drawings:

Figure 1 is a longitudinal section through one end of an open hearth steel making furnace equipped with the burner of my invention.

Figure 2 is an enlarged plan view of the improved burner with parts broken away and shown in section in the interest of clearness.

Figure 3 is a vertical longitudinal section of my improved burner taken on line II[III of Figure 2.

Figure 4 is a transverse section taken on line IV'IV of Figure 3.

Figure 5 is a front end elevation of the burner as viewed from the left of Figure 3.

Figure 6 is a rear end elevation of the burner as viewed from the right of Figure 3.

Figure 7 is a fragmentary detail of one end of the pipe through which the gaseous fuel is discharged from the burner.

Figure 8 is an end elevation of Figure '7 as viewed from the left end thereof.

Figure 9 is a detail of a-cover plate adapted to be secured to the beveled end of the gaseous fuel' Figures l4, 15, 16 and 17 are diagrams illustrating the action of another conventional burner.

Figures 18, 19, 20 and 21 are diagrams illustrating the herein claimed burners action.

Referring in detail to the drawings, reference numeral l0 represents the hearth of a conventional open hearth furnace having a roof l2, and a combustion chamber I6 communicating with an air uptake it. As is well known to those skilled in the art, in the normal operation of an open hearth furnace, the path of the gases is periodi cally reversed. Thus the air uptake 16 at one time serves as an air inlet and at another period of the cycle serves as an outlet for the spent gases which are led through the usual regenerator so as to give up the heat thereto. It is common practice in open hearth furnaceoperatlon, therefore, to periodically reverse the flow of the gas while the burner II, as shown in Figure l, is active. Because of the active and inactive periods of burner operation, there is an inherent problem to be overcome in the normal operation of burners fired with a combination of liquid and gaseous fuel due to the tendency of the inactive burner at the outgoing end of the furnace to become clogged with particles of slag, dirt, or other foreign matter. When such foreign matter accumulates in the outlet orifices of the burner, it has a tendency to interfere with the proper burner operation. For this reason. the burner of my present invention is so constructed and arranged that there is a minimum tendency for forei n matter to collect at the outlet orifices of the gaseous and liquid fuel pipes. Special means are provided to expel any accumulations which may precipitate in a region of the outlet orifice of the gaseous fuel pipe. The best utilization of the heat from the gaseous fuel flame, in heating the bath, is secured by blanketing and holding it down with the liquid fuel flame. The blanketing also prevents the aseous flame from rising up and damaging the refractory roof.

Referring more particularly to the drawings,

the novel burner comprises an outer cylindricalshell-like casing which may conveniently be constructed of a ten-foot length of stock-size 12- inch steel pipe closed at its front end by longitudinally offset closure plates 22 and 24 and at its rear end by a closure plate 26. The front closure plates 22 and 24 are offset longitudinally. As thus constructed. the front end of the burner has an upper forwardly extended portion from which the atomized liquid fuel such as oil or tar is discharged. By thus disposing the liquid fuel outlet orifice forward of the orifice through which the gaseous fuel is discharged, I effectively prevent the accumulation of gummy deposits of dripping oil or tar while the burner is inactive. A gaseous fuel pipe 28 is disposed coaxlally of the shell 20 and it extends through a central opening 30 formed in the rear closure plate 26. This gaseous fuel pipe is conveniently formed of a straight piece of standard stock 6-inch pipe about eleven feet long. The forward portion of the pipe 28 is cut or beveled ofl downwardly and forwardly at an angle, as indicated at 32 in Figure 7, and welded or otherwise secured to said beveled end there is a flat cover plate 34. The front extremity of the pipe 28 is welded or otherwise secured to the rearmost front closure plate 24, and the front extended lip 38 of the cover plate 34 is extended forwardly and welded or otherwise se- I cured to the lower edge of the frontmost closure plate 22. As thus arranged, approximately the lower half of the pipe 28 and the lip 36 of the cover plate 34 jointly define a substantially semicircular gaseous fuel outlet orifice, as indicated at 38. This creates a throttling effect at the gas nozzle and increases the velocity of the gas flow proportionally. The semi-circular outlet orifice having an arcuate bottom and straight top, as

. fuelshown and described, in combination with a straight bottom wall portion of the gaseous fuel pipe 18, provides a construction which can be readily kept clean, in a manner hereinafter set forth. The fiat contour of the orifice at the top and the downward inclination of the plate 34 is advantageous inthat thus the coke oven gas is discharged downwardly or at an angle to the line of discharge of the liquid fuel, promoting combustion of both fuels in close proximity to the bath, while at the same time keeping the flame away from the roof, thus protecting the refractories in the roof. The prime reason for directingthe gas flame downward is to control its position in relation to the bath.

One problem in the normal operation of prior art burners using both liquid and gaseous fuels has been to overcome the tendency toward clogging the liquid fuel nozzle when it is located within the gaseous fuel nozzle. Another problem is the tendency toward excessive condensation of the atomizing steam in the atomizedliquid fuel pipe when that pipe passes through the length of the coolant chamber outside the gaseous fuel pipe and is subjected to cooling action of the circulating coolant. Any dirt accumulation on the nozzle will deflect and deteriorate the liquid fuel flame. Condensation of atomizing steam will necessitate increasing steam-liquid fuel ratio, which will reduce the heating efficiency of the liquid fuel flame. To overcome these damaging tendencies, I provide in the improved burner an arrangement wherein the greater portion of the atomized liquid fuel pipe 4!! lies in the gaseous fuel pipe 28 where it is shielded from the cooling action of the circulating coolant in the shell 20. The nozzle 44 of the atomized liquid fuel pipe 40 is located outside of and above the gaseous fuel nozzle 38 where it is not so exposed to the clogging accumulation of slag and dirt as if it-were located within the nozzle 38.

The atomized liquid fuel, being under pressure, has considerable velocity as it leaves the nozzle 44. The gas is also under pressure, and since there is a reduction of section at the nozzle 38, the gas is discharged at sufficient velocity to produce a controllable flame. If the discharge velocity is low, the flame becomes sluggish. The discharge velocities of the two fuels are different, and it is therefore advisable that they do not come in contact too soon after leaving the nozzles which might disrupt the smooth propagation of the flame.

Secured to the rear extremity of the gaseous pipe 28 there is a T or other suitable fitting 46 having a branch 48 leading to a gaseous fuel supply duct 50 which is connected, for example, to a source of coke oven gas. A nipple 62 extended rearwardly from the fitting 48 has secured thereto a flange 54, and bolted or otherwise secured to the flange 54 is a closure disc 56. The disc 58 has a hub portion 58, and the hub and the disc are provided with suitable aligned openlugs to permit the passage therethrough of the rear extremity of the liquid fuel pipe 40. A suitable gland 60 serves to make a gas-tight sliding connection between the closure disc 56 and the atomized liquid fuel pipe 40 which is exposed to a wide temperature range and is therefore subject to considerable.expansion and contraction. An atomizer 82 of known construction is screwed or otherwise secured to the rear extremity of the liquid fuel pipe 40. Connected with this atomizer is a liquid fuel inlet supply duct 88. Also connected to theatomlzer 82 is a pipe flce of the gaseous fuel pipe during the inactiveperiod of the burner. The steam scavenger pipe 88 and the liquid fuel pipe 48 pass through respective holes I2 and 14 formed in pipe. holders- 18 which are welded or otherwise secured in slots 18, cut in the upper wall portion of the gas pipe 28.

To facilitate the ejection of any accumulation of foreign matter which is not readily expelled by the steam scavenging jet, I provide means for introducing a cleaning rod. For this purpose, a suitable hole 88 is provided in the rear closure disc 58 and hub 58, this hole being normally closed by a screw plug 82. Thus, by merely removing the plug and inserting a rod through the hole 80, the cleaning out of any accumulated or adherent deposits in the gaseous fuel pipe 28 can be readily efiected. Scavenger pipe 68 -will have a gas-tight packing gland iiii at the point where it passes through the hub portion 58 of the disc 56 to provide a sliding flt for adjustably moving the scavenger pipe 88 back and forth.

- In operation, after the idling period a short blast of steam is sent through the scavenger pipe 88 and nozzle 18 to blow out any accumulation of dirt in the nozzle 38. Another blast of steam is then blown for a few seconds through the liquid austere di h r ed from the nozzle end II of the scavenger steampipe. The nozzle ll of the scavenger pipe 88 is cut on an angle parallel to the gas fuel pipe 28, as shown in Figure 3, to prevent lts being clogged by slagor dirt entrained in the waste gases similar to the manner in which the liquid fuel'pipes located in the gaseous fuel pipes ofsome present type burners are now be ins c assed. In those rare occasions when the nozzle outlet oriflce of the gaseous fuel pipe does become clogged, the foreign matter can be removed by .a cleaning bar inserted manually through the hole 88 upon removal of the closure plug 82. Thus it is apparent that construction and arrangement of the parts shown and described makes available the several obiectivesof the invention referred to in the opening paragraphs of this specification.

fuel pipe 48 to clean it out. The burner is then ready to operate and the gas fuel, liquid fuel and V .atomizing steam valves are opened.

Water or other coolant is introduced into the interior of the shell 28 through a pair of inlet pipes 8| which pass through suitable holes formed in the rear clcsure disc 26. These pipes rest near their inner ends on the notched lugs '88, welded or otherwise secured to the lower wall portion of the shell 28. The cooling water passes out through suitable pipes ,connected to outlet spuds 88, welded or otherwise secured to the uD-' and the rear closure disc 58 is entirely enclosed.

within the gaseous fuel pipe and is thus shielded from the direct action of the coolant circulated through the shell 28.

The semi-circular or'half-moon shape of the outlet orifice 38 of the gaseous fuel pipe is designedly intended to produce a, flame of the desired shape and in proper predetermined an lar relation to the oil flame emanating from the outlet orifice oi the liquid fuel pipe 48. As above;

suggested. the offset relation of the'front clo-' sure plates 22 and 28 and the projecting over- The improved burnerproduces a flame which is proper in direction, size and shape and correctly positioned to obtain maximum efficiency in heating the bath without adverse effects on the refractories of the furnace.

In the'herein claimed burner; steam condensation in the liquid fuel pipe will be minimized by reducing the amount of the pipe exposed to the coolant in the shell. Elimination ofcondensation reduces proportionally the total amount of steam required for proper atomization of the liquid fuel. Condensation in the atomizedliquid fuel pipe will adversely affect the atomization and necessitates the use of additional steam to maintain the atomization. Any reduction in the amount of atomizing steam used is reflected in a liquid fuel flame of higher temperature and increased radiation intensity. My improved burner construction lends itself to the proper relative positioning of the liquid fuel nozzle outside of and above the gaseous fuel nozzle whereby the heavier liquid fuel flame forms a. protective blanket over the lighter gaseous .fuel flame.

During that part of the cycle when the burner is idle it is exposed to waste gases which are directed at it from the opposite active burner. These waste gases carry a certain amount of slag, dirt, etc. which accumulate in and clog the nozzles. The liquid fuel nozzle 44 presents a small target for the dirt and thereforethe accumulation is small. The gas fuel nozzle 38 on the other hand is large and considerable dirt enters at the nozzle 38 of the pipe 28 where it accumulates on the bottom. When the gas flow is shut off a certain amount of vacuum is created inside pipe 28 which tends to draw the waste gases in through the nozzle 38 with the entrained dirt. .This vacuu'm condition is what causes the excessive fouling of the liquid fuel nozzle in the type of burner where that nozzle is located inside the gas fuel nozzle. This is also the reason for cutting the nozzle 18 of the scavenger pipe 88 at an angle as shown in'Figure 3 ofv the application. In practice, during the idle period of the burner, so much waste gas enters pipe 28 that pipes to and 88 become heated to a cherry red. The improved action of my herein claimed 7 .burner, as compared with that of two old conhanging lip 38 extended from the forward end of H the closure plate 84, provides an arrangement of structure which prevents oil or tar from pipe from dripping down and lodging directly on 7 any part of the front end of the gas pipe and thus effectively serves to prevent clogging. Any dirt or foreign matter lodged in the gas fuel orifice 38 can be readily ejected by a jet of steam ventional types of burners, can be readily visualized by reference to Figures 11 to 21 inelusive; Figures 11, 12 and 13 illustrate the action of one conventional coaxial nozzle type of burner. Figures l4, 15, 16 and 17 illustrate the action of anothef conventional, type of burner in which liquid fuel is discharged above a nozzle from which gaseous fuel is discharged. Figures 18, l8,

20 and 21 illustrate the action of my herein described burner.

Referring first to the action of nozzle type of burner of Figures 11 through 13, the liquid fuel nozzle is located within the gaseous fuel nozzle as indicated by the concentric circles marked Liquid fuel and "Gaseous fuel in Figure 11. Figure 11 shows the relative positions of the fuels as they leave the nozzles. The liquid fuel, having weight and velocity, travels on a flat trajectory, while the gaseous fuel, being light, slows down and tends to rise, as indicated by the outer eccentric circle marked "Gaseous fuel in Figure 12. Figure 13 illustrates conditions after the liquid fuel flame has developed, and it is to be noted that most of the gas flame has escaped to a position above, where it is now useless for heating the bath, and can rise to overheat the refractory of the furnace roof.

In the conventional type of burner shown in Figures 14 through 1'7, the liquid fuel nozzle is located above the gaseous fuel nozzle. The gaseous fuel nozzle is formed by flattening a normally circular gaseous fuel pipe to an elliptical shape wlth practically no reduction in the crosssectional area of the pipe. Figure 15 illustrates the condition as the flames come together. Figure 16 illustrates the condition as the gas flame starts to rise and the liquid flame starts to flatten and bear down. Figure 17 illustrates the condition of this conventional type of burner, showing that only a thin layer of gas remains for useful heating of the bath, while the remainder is rising toward the roof.

The improved action of my herein described and claimed burner is illustrated in Figures 18 through 21. It will be recalled that in my improved burner the liquid fuel nozzle is located above the gase fuel nozzle. It will be seen in Figure 18 that the gasnozzle is approximately semi-circular in shape. The sectional area of the gas fuel pipe in my burner is considerably reduced at the nozzle outlet, and thus increases the gaseous fuel velocity. Figure 19 illustrates the conditions in my improved burner when the flames begin to develop but have not yet come together. Figure 20 illustrates a later stage after the flames have come together and begun to flatten out. The outline marked Gas, it will be noted, has thin outer feather edges and thus contains very little gas flame to escape upwardly short front end portion extended through said inthe coaxial said shell and having a longer portion located within said gas pipe and thus shielded thereby from the coolant. and respective fuel supply conduits communicating with said gas and liquid fuel pipes.

2. A combination gas and liquid fuel burner,

' comprising a shell structure forming a coolant toward the roof. Figure 21 illustrates the condition after the liquid fuel flame has spread out considerably to blanket the bulk of the gaseous fuel flame and thus hold it down where it will most effectively heat the bath. It will be noted that there is very little gas in the outer feather edge portions to escape upward around the liquid fuel flame. Thus by comparison of the diagrams of the three burners illustrated, it is apparent that my improved burner more effectively blankets the gas flame and thus more effectively shields the roof, and at the same time exerts a greater heating effect on the bath.

- Various modifications may be made by those skilled in the art without departing from the invention as defined in the appended claims.

chamber. a round gas pipe therein having a forwardly and downwardly inclined flat top wall at the discharge end thereof which in part defines the outlet orifice of the gas pipe, a liquid fuel pipe whose outlet orifice is spaced above and located in a plane spaced in front of the plane of the outlet orifice of said gas pipe, said liquid fuel pipe passing through said inclined wall and being enclosed by and shielded at the rear portion thereof from the coolant in said shell by said gas pipe, and respective fuel supply conduits communicating with said gas and liquid fuel pipes.

3. A combination gas and liquid fuel burner, comprising a shell structure forming a coolant chamber, a round gas pipe therein having a forwardly and downwardly inclined fiat top wall at the .discharge end thereof which in part defines a substantially semicircular orifice of the gas pipe, two longitudinally offset front closure plates secured to the front portion of said shell, a liquid fuel pipe whose outlet orifice is in the plane of the one of said closure plates at the extreme front end of said shell, the outlet orifice of said gas pipe being in the plane of the other of said offset closure plates, and respective fuel conduits communicating with said gas and liquid fuel pipes,

4. The burner as defined in claim 1, having a scavenger pipe located within said gas pipe and having its outlet end adjacent the outlet orifice of said gas pipe, and a fluid pressure supply pipe communicating with said scavenger pipe.-

,5. A combination gas and liquid fuel burner, comprising a shell having two longitudinally offset front wall closure plates and a rear closure element secured to the shell, said shell. plates and element jointly forming a coolant chamber, a coolant supply pipe terminating adjacent the front closure plates, 9. gas supply pipe extending through said rear closure element and terminating at the one of said front closure plates offset rearwardly from the plate at the extreme front end of said shell, the front portion of said gas supply pipe being beveled downwardly and forwardly, a downwardly and forwardly inclined cover plate secured to said beveled portion and having a front lip secured to the one of said front closure plates at the extreme front end of said shell, said cover plate and the front end of said gas pipe jointly defining a. substantially semicircular outlet gas orifice, a liquid fuel pipe extending through said cover plate and through the one of said closure plates at the extreme front end of said shell, said fuel pipe being directly exposed to the coolant in said shell only between said cover plate and said extreme front end plate. a portion of the liquid fuel pipe to the rear of said cover plate being located within said gas pipe and thus shielded thereby from the coolant in end of the burner, a downwardly and forwardly inclined cover plate secured to the beveled end of said gas pipe, a liquid fuel pipe having a relatively said shell.

6. The burner defined in claim 5, with a fluid pressure scavenger pipe terminating adjacent the outlet orifice of said gas pipe and adapted to facilitate the expulsion of foreign matter from I said'orifice.

. ZDENEK J. HAUZVIC. 

